1. Field of the Invention
The present invention relates to a hydrogen sensor for detecting hydrogen concentration in a gas.
2. Description of the Related Art
As a related art, a hydrogen sensor utilizing a hydrogen-absorbing alloy is disclosed in JP-A-10-73530. The hydrogen sensor has a hydrogen-absorbing alloy bonded on one surface of its substrate and has a strain gauge attached on the other surface thereof. In this arrangement, the distortion is produced in the substrate under a circumstance of volume expansion caused in the course of absorbing hydrogen by the hydrogen alloy. The hydrogen sensor detects the amount of said absorbed hydrogen by the strain gauge on the basis of a magnitude of distortion of a substrate. The hydrogen sensor utilizing such a hydrogen-absorbing alloy shows fairly high selectivity of hydrogen, whereby the hydrogen sensor has an advantage of high detection accuracy.
The hydrogen sensor as disclosed in JP-A-10-73530 is suitable for detecting an amount of hydrogen, for instance, in such a way of being incorporated in equipment utilizing a hydrogen-absorbing alloy (e.g., hydrogen-absorbing alloy tank); however, the sensor is incapable of detecting a hydrogen concentration in a gas.